| | Re: How much light is needed to culture blackworms?
I keep them without any light besides what filters in through the window. They like a lot of air so an air stone in addition to a sponge filter is a good idea unless you keep the water really shallow, but less water means it pollutes faster so I just aerate deeper water better. The sponge filter prevents you from having to do so many water changes. I throw in expired fish food or uneaten fish/snail food. Just a little bit.
They don't like sand, they like large gravel much better. They like to hunker down in it, eat what collects there and wedge their ends in so they can wave in the current (ew).
To harvest them, turn off the air and in a little while, they'll start sticking up out of the gravel and you can grab them with tweezers or suck them up with a turkey baster.
I've only done this is a 1 gallon tank. I have yet to try it in a larger tank. So, based on my tiny tank experience, they're really slow to reproduce. To keep up a worthwhile supply, you've got to put them in a pretty large set up.